Method and apparatus for supplying current to exciter lamps



June 30, 1942. G, F 1 JR 2,287,981

METHOD AND APPARATUS FOR SUPPLYING CURRENT TO EXCITER LAMPS Filed March 16, 1940 2 Sheets-Sheet 1 INVENTOR George Friedl Jr:

ATTO R N EY June 30, 1942. FRlEDL JR 2,287,981

METHOD AND APPARATUS FOR SUPPLYING CURRENT TO EXCITER LAMPS 2 Sheets-Sheet 2 Filed March 16, 1940 INVENTOR 6 f Z J. sorgegg? r ATTORNEY Q Patented it... so, 1942 UNITED STATE s PATENT. orrlcai f METHOD AND APPARATUS FOR SUPPL YING CURRENT TO EXCITEF, LAMPS George Friedl, Jr., Fanwood, N. J., assignor to International Projector Corporation, NewYork, N. Y., a corporation of Delaware Application March 16, 1940, Serial No. 324,317

19 Claims.

An additional feature of the present invention is the provision of means for rapidly switching the type and value of current supplied to the various exciter lamps. 1

Other features and advantages will become apparent from'the following description and the drawings in connection therewith in which,

- Fig. l is a schematic diagram of current supply equipment embodying the present invention.

Fig. 2 is a continuation of Fig 1 and is a schematic diagram of the switching circuit employed are usually supplied with smooth direct current so that there are no fluctuations in the-current passing through the exciter lamps to affect the sound emitted by the sound reproducingequipment. Since the usual source of current supply is alternating current, such current is usually rectified and filtered before being supplied to the exciter lamps. Rectifying equipment for this purpose is comparatively expensive and, therefore, in order toavoid the cost of duplicate rectifying equipment, as well as the additional'operating and maintenance expenses entailed thereby, the present invention provided for a single rectifying unit which only supplies rectified current for the lamp in the "on" machine while unrectifled current is supplied to the lamp .on the "off" machine. When, however, a theatre is equipped with only one rectifying unit for the exciterlamps, sound outages resulting from the breakdown thereof may occur. To prevent such outages the present invention provides means for operating the exciter lamp of the on machine as well as the "off machine on alternating current during such emergency.

Another feature of the present invention is the provision of means for heating an exciter lamp with alternating current preliminary to its operation. The preheating current supplied is less than the usual operating current and such preheating serves to prevent thevshock resulting to a cold lamp when a full operating load is applied thereto.

Still another feature of the present invention is the provision of means in a sound reproducing device not in use for preheating one exciter lamp with alternating current at a temperature reduced' from its normal operating value while operating the exciter lamp in the sound reproducing device in use at its normal operating value with direct current.

A further feature of the present invention is the provision of means for rapidly increasing the preheating current from the reduced value to avalue equal to the operating current.

in connecting the equipment illustrated in Fig. 1

' to two exciter lamps.

Referring now to Fig. 1' the current from one side of a: source of alternating current supply,

such as a power line I0, is connected through a' circuit breaking switch II and a suitable fuse i2 to one arm l3 of a double pole double throw switch It. One of the associated poles I5 of the switch I is in turn connected to one end of the primary ii of a transformer ll forming a part of a full-wave rectifier. The other end of the primary I6 is connected directly to the other side of the source of alternating current supply Ill. Taps for regulating voltage output may be provided on the primary. The secondary of transformer ll includes two small coils l8 and I! which supply current for heating the filaments of rectifying tubes 20 and 2|, respectively. Said rectifying tubes may be of the type known commercially as Tungar tubes. The main coil 22 of the secondary has a center tap 23 and a numberof end taps 30. The center tap 23 may be connected through choke coils 24 and 25, and through ballast lamp 26, test strap 21 and rheostat 28 to pole 29 of the double pole double throw switch I4. .When the movable arms of the double pole double'throw-switch H in contact with the poles 29 and i5, pole 29 is connected to the output terminal 3| through the arm 32 of switch l4.

Movable arms 33 and 34 are arranged adjacent the ends of the coil 22 to make contact with a selected one of the taps 30 adjacent thereto. The movable arm 33 is connected to the filament in rectifying tube 2| and movable arm 34 is in turn connected to the filament of rectifying tube 20. The plates of the two rectifying tubes' are connected together and nal 35.

Suitable condensers 36 and 31 are arranged in the filter circuit, condenser 36 being connected at one end thereof to the plates of the rectifying tubes and at the other end to a point in between choke coils 24 and 25, and condenser to an output termipotential may be 31 being connected on one side thereof to the plate of the rectifying tubes and on the other side thereof to pole II of the double pole double throw switch l4. Rheostat 33 is connected between the plates of the rectifier tubes and the terminal of the strap 21 adjacent the ballast lamp 23.

The foregoing equipment completes the rectiiler circuit. The transformer II supplies alternating current of proper voltage. The coils II and II of the secondary serve to furnish current for the filaments of the rectifying tubes 33 and II, the main coil 22 supplying the current which is rectified, the current being rectified through the rectifying tubes 20 and 2| and smoothed out by the filter circuit including choke coils 34 and II, and condensers '33 and 31." The rheostat 23 serves to control the amount of direct current supply and also cooperates with 33 in maintaining on ballast lamp 23 the voltage and current value at which the ballast lamp is designed to operate. The taps on the primary and secondary of transformer may be adjusted so that the movable arms on rheostats 23 and 38 are usually at their center positions thus providing a range on both sides of the center positions for subsequent adjustments. The test strap 21 is designed to be removed from the circuit for inserting an ammeter therein to measure the direct current output.

I' or supplying alternating operating current.

and alternating current of a value less than operating current for preheating purposes, the stepdown transformer 33 is provided. One side of the primary of transformer 39 is connected directly to one side of the source of alternating current It, the other side of the primary 39 being connected to the other side of the alternat ing current supply ll through a suitable fuse 40 and switch Ii. It will be seen that when switch II is open no current will be supplied either to the rectifying circuit or to the alternating current supphr circuits. Taps may be provided on the primary of transformer 39 for adjusting the voltage on the secondary.

The secondary of transformer 38 is tapped intermediate its ends, this tap 4| being so located on the secondary that the difference of potential between tap 4| and one end 42 of the secondary is less than the difference of potential being between tap 4| and the end 43. For instance, the difference of potential between tap 4| and end 42 may be two volts while the difference between tap 4| and end 43 may be 9 /2 volts. The lower used when preheating an exciter higher potential may be used said lamp at full brilliance. End 42 is connected to an output terminal 44. Tap 4| is connected to output terminal 35 and end 43 is connected through a rheostat 45 to the terminal 33 of the double pole double throw switch l4. It will be seen that when the double pole double throw switch is in its upper position as illustrated in Fig. 1 so that switch arm 32 contacts pole 48 that the end 43 of the secondary coil of transformer 39 will be connected to output terminal 3|. The rheostat 45 regulates the alternating operating current delivered at output terminals 3| and 35.

While I have illustrated and described transformer 30 as being a single transformer having a tapped secondary, it will be understood by those skilled in the art that two transformers may be substituted as equivalent thereto, one of said transformers having its secondary connected in lamp while the when operatin the same positionas 4| and 43 and of said transformers having its nectedin thesamepositionas 4 an 43.-

From the foregoing it will be apparent that when the double pole double throw switch I4 is in its lower position as viewed in Pig. current will be supplied to the rectifying circuit and the rectifylus circuit will in turn supply direct current at output terminals 3| and 3|. On the other hand, when the movable arms of the double pole double throw switch 4 are in their upper position the alternating current supplied to the rectifying circuit will be cut 0! and the recti- 3l. while in place thereof, alternating current for operating the exciter lamp will be supplied at output terminals 3| and 3|. Furthermore, it will be evident that, whatever the position of the movable arms of the double pole double throw switch 4, preheating altematingcurrent, of less value than the operating current, will be constan'tly supplied at output terminals 33 and 44. It will, therefore, be seen that operating current either director alternating is supplied at terminals 35 and 3| and preheating current is supplied at terminals 3! and 44. Thus terminal 38 is common to both the preheating and operating current supplies.

In the present specification and in the appended claims the phrase operating current" when used in relation to current supplied to a light source or an exciter lamp signifies current of a value sufiicient to cause said light source or exciter lamp to light with full brilliance, this being the usual condition of such light source or exciter lamp when the sound reproducing apparatus in which it is employed is functioning to rethe other secondary conproduce sound.

connected to the adjacent pole 53 In Fig. 2 is illustrated a switching arrangement for supplying the current derived from the output of the apparatus illustrated in Fig. 1 to two exciter lamps, the preheating current being supplied to one lamp, and the operating current to the other lamp, said switching arrangement being adapted to reverse the supply of current to the lamps.

-As is stated hereinbefore, output terminal 3| is common to both the preheating and the operating current supplies. The output terminal 3! is connected to one terminal 41 of exciter lamp 48 and to one terminal 43 of exciter lamp II. The output terminal 3| for supplying operating current is connected to one pole ll of a double pole double throw switch '2, the output terminal 44 for supplyin preheating current being of said switch. Pole 53 is connected with its diagonally opposite pole 54 and pole ii is connected with its diagonally opposite pole II. It will be seen that when switch 52 is thrown to the left as viewed in Fig. 2 theupper movable arm 58 of switch 52 will be connected to output terminal 44. In the same position of the switch the lower arm I! will be connected to output terminal 3|. When the switch is moved to the right as viewed in the same figure the connections will be reversed, arm 56 being connected to output terminal 3| and arm 51 being connected to output terminal 44. Arms 56 and 51 may be connected to the movable arms of a switch 58, the poles of which are connected together in the same fashion as the poles of switch 52. One pole it is connected to the terminal of exciter lamp 48 and the adjacent pole 6| is connected to the terminal I! of exciter lamp ll.

pole 19 to lamp 61.

It will.be seen that with both switch arms in the left hand position as viewed in Fig. 2, operating current will be suppliedto' exciter lamp 50 and preheating current will be supplied to lamp 48. It will also be apparent that by moving the movable arms of either switch into an opposite position the current supplied to the lamps l8 and 50 will be reversed.

While I have described two switches 82 and 58 as being arranged in the circuit it will readily be understood that one switch may be dispensed with and the switching operati'on controlled solely by the other. However, for the purpose of controlling the current points the arrangement of two or more switches in the circuit is desirable. As many switches as are desired can be inserted in the sug ested manner into the switching. circuit, each switch acting to interchan e the current supplied to the lamps without rating any other switch. Furthermore, switches 52 and 58 maybe mechanically interlocked with switches 48 and 52 described in a co-pending application bearing Serial No. 324,280,-fi1ed March 16, 1940, entitled "Method and apparatus for electronic changeover, Fowler Durst, inventonso that by a single manual operation a change may be effected not only from an exciter lamp in one machine to an exciter lamp in another machine but also from a sound reproducing apparatus in the first machine to the sound reproducing apparatus in the other. When such switches are alsomechanically interlocked with dowser controls, a quick changeover can readily be effected from one projecting machine to another.

Where there are three machines each having its own exciter lamp another switching arrangement may be employed for supplying current thereto. This arrangement is illustrated in Fig. 3.

As stated hereinbefore, current for operating an exciter lamp is obtained at terminal 3! and common terminal 35. Current for preheating an exciter lamp is obtained at terminal 65 and the common terminal 35. Terminals 6B and 3! are connected to a series of double pole double throw reversing switches 63, as and 65. The connection of these switches to terminals M and 38 are the same as those hereinbefore described in relation to switches 52 and 58 with the exception that there is one extra reversing switch. The common terminal 35 is each of the exciter lamps 66, 67, and 68.

The arms 69 and iii of reversing switch 65 are connected to arms II and 12, respectively, of a selector switch I3. Arms ii and 12 are each associated with three poles, said arms being 'mechanically interlocked although not electrically connected together. The selector switch I3 may be a "Yaxley switch such as that described in Patent No. 1,975,247. Poles Hi, 15 and i associated with arm ii are connected to exciter lamps 66, 61, and 68, respectively. Poles 11, I8, and 19 associated with arms 12 are also connected to these lamps, but in the following order: pole TI to lamp 68, pole 18 to lamp $6,

It will be seen the position illustrated in Fig. 3 operating current will be supplied to lamp 66 and preheating current to lamp 61. Lamp 68 will not have any current supplied to it. It will be immediately apparent that by switching one of the reversing switches 63, 64 or 65 that the current supplied to lamps 66 and 61 will be interchanged with connected to one side of that with all the switches in supply from diflerent V suppl current for p eheating purposes being supplied to lamps 88 and current for operating purposes being supplied to lamp 61.

When the selector switch 13 is moved so that arm II is in contact with pole I4 and arm 12 is in contact with pole ll, lamps 86 and 88 will be connected to the current supply while lamp 6'! will be disconnected. Preheating currentwill be supplied 'to one of the lamps 68 or 88 and operating current will be supplied to the other of said lamps. By operating one of the reversing switches the current to these two lamps may be interchanged.

When selector switch I3 is moved so that arms Ii and 12 are in contact with poles 16 and I8. respectively, lamps 68 and 61 are connected to the current supply and lamp 66 is disconnected therefrom. Preheating current is supplied to one of said lamps and operat current is supplied to the other lamp, operation of any of the reversing switches interchanging the current y. a It will thus be seen that by operating the selector switch 13 any two of the three lamps may be connected to the current supply and thereafter the current supplied to either or the two selected lamps may be interchanged by operation of any one of thereversing switches 63, 64 or 65. From the foregoing description it will be apparent that theswitch arrangement illustrated in Fi 3 may be extended to control and supply current for more than three exciter lamps.

Where it is desired that the exciter lamp on the off machine be adjusted, preliminary to switching said machine to on" operation, it is necessary to bring said lamp to a state of full brilliance by supplying sumcient current therefor. To accomplish this I prefer to interpose a single pole double throw switch 88 in the connection between terminal 44 and end 52 of the secondary of transformer 39. Arm 86 of switch 80 may be connected to terminal 54. Pole 82 of switch 80 may be connected to and d2 of the secondary of transformer 39. Ordinarily arm at is in contact with pole 82 and the current supplied at temiinals M and is only sufllcient to heat an exciter lamp preliminary to its operation. When, however, it is desired that the exciter lamp connected with terminals as and 35 be adjusted-preliminary to regular operation in an on machine, arm 8! is arranged to make contact with pole 83. Pole 83 is connected to end 43 of the secondary of transformer 39 and at end 43 and the center tap M current of full operating value is obtained. It will be noted that pole 83 is connected directly to end 43, thereby avoiding the drop in potential arms resistor 55.

From the foregoing description lt will also be apparent that I have provided current supplying equipment for use with an alternating current supply source, which equipment is adapted-to supply direct operating current for one exciter lamp and alternating current for heating another lamp preliminary to its operation and, furthermore, that I have provided means for interdirect current for operation of exciter lamps and also designed to substantially.immediately supply alternating current for operating exciter lamps. With said alternating current operating supply I have also provided alternating current supply for heating an exciter lamp pre to its operation as well as for interchanging the supply of current to the various lamps.

It is also to be understood that while I have\ described transformer 39 as supplyingralternating current of "operating value for emergencies, such current may be employed for regular as well as emergency operation with exciter lamps of sufficient thermal lag.

While a preferred embodiment of my invention has been described it is to be understood that this description is not a limitation upon the scope of the invention, which is to be determined only -by the appended claims.

claim. K

1. In combination, an alternating current power supply line, a plurality of light sources, arectifier having its input connected to the power supply line, said rectifier being adapted to supply direct current for operating a light source, a

transformer having its primary connected to said powersupply line and having a first part of its secondary .adapted to supply alternating current for operating a first of said light sources, and having a second part of its secondary adapt- ..ed to supply alternating current for heating a first part of the secondary of the transformer to the first light source.

2. In combination, an alternating. current power supply line, a plurality of light sources, a rectifier having its input connected to the power supply line, said rectifier being adapted to supply direct current for operating a light source, a

transformer having its primary connected to said power supply line and having a first part of its secondary adapted to supply alternating current for operating a light source, and having a second part of its secondary adapted to supply alternating current for heating a light source preliminary to operation, the second part. of the secondary being connected to a first light source, the output of the rectifier being connected to a second light source and switching means for disconnecting the input of the rectifier from the power supply line and connecting the first part of the secondary of the transformer to the first light source after disconnecting the second part of the transformer secondary therefrom. I

3. In combination, an alternating current power supply line, a plurality of light sources, a rectifier having its input connected to the power supply line, said rectifier being adapted to supply direct current for operating a light .source, .a transformer having its primary connected to said power supply line and having one part of its secondary adapted to supply alternating current for operating a light source, and having a second part of its secondary adapted to supply alternating current for heating a light source preliminary to operation, the second part of the secondary being connected to a first source, the output of the rectifier being connected to a sec-- ond light source and means for substantially simultaneously disconnecting the output of the rectifier from the second light source and connecting the first part of the transformer secondary to the second light source.

4. In combination, an alternating current 75 power supply line, a plurality of light sourcu, a. rectifi er having its input connected to the power supp ine.- said rectifier being adapted to supply direct current for operating a light source,

a transformer having its primary connected to said power supply line and having one part of its secondary adapted to supp y alternating cur rent for operating a light source, and having a second part of its secondary adapted to supply alternating current for heating a light source preliminary to operation, the second part of the secondary being connected to 'a first light source,

the output of the rectifier being connected to a second light source and switching means for disconnecting the output of the rectifier from the second light source and connecting the first part of the' transformer secondary to the first 3 light source after disconnecting the second part of the transformer secondary therefrom.

5. In combination, an alternating current power supply line, a rectifier, a transformer, the

I input of the rectifier and transformer being connected. to the power supply line, a plurality of light sources, the output of the rectifier being connected to one of said light sources, the output of the transformer being connected'to a sec- 0nd of said light sources and means for disconnecting the output of the rectifier from the firstmentioned light source and connecting the output of the transformer to said first-mentioned light source.

6. In combination, an alternating current power supply line, a rectifier, a transformer, the input of the rectifier andtransformer being cone nected to the power supply line, a plurality of light sources, the output of the rectifier being connected to one of said light sources, the output ofthe transformer being connected to a second of said light sources and means for disconnecting the output of the transformer from the second-mentioned light source and connecting the output of the rectifier to said secondmentioned light source.

7. In combination an alternating current power supply line, a rectifier, a transformer, the

input of the rectifier and transformer being connected to the power supply line, a plurality of light sources, an electrical circuit connecting the output of the rectifier to a first light source and the output of the-transformer to a second light source, means arranged in the circuit for switching the output of the rectifier to the second light source and the output of the transformer to the first light source.

8; In combination an electric power supply line, a rectifier, a transformer, the input of the rectifier and transformer being connected'to the power supply line, a plurality of light sources, one light source connected to the output of the rectifier, another light source connected to the output of the transformer and switching means for interchanging the connections of the output of the rectifier and the output of the transformer to the light sources.

9. The method of operating a pair of light sources which comprises supplying alternating current of Operating value. to one light source while heating the second light source prelimi 10. In combination an electric power supply line, a rectifier, a transformer, the rectifier and transformer being connected to the power supply line, a plurality of light sources, one light source connected to the output of the rectifier, another light source connected to the output of the transformer, said rectifier being adapted to supply direct current for operating a light source, said transformer being adapted to supply alternating current forheating a light source preliminary to operation, and switching means for interchanging the connections of the output of the rectifier and the output of the transformer to the light sources.

11. In combination an alternating current power supply line, a rectifier, a transformer, the input of the rectifier and transformer being connected to the power supply line, a plurality of light sources, the output of the rectifier being connected to one of said light sources, the output of the transformer being connected to asecond of said light sources, said rectifier being adapted to supply direct current for operating a light source, said transformer being adapted to supply alternating current for heating a light source preliminary to operation, and means for disconnecting the output ofthe rectifier from the first-mentioned light source and connecting the output of the transformer to said first-mentioned light source.

12. In combination an alternating current power supply line, a plurality of light sources, a rectifier, the input of the rectifier connected to the power supply line, said rectifier adapted to supply direct current for operating a light source, a transformer having its primary connected to the power supply line and having a tapped sec ondary adapted to supply, at the tap and one end of the secondary, alternating current for operating a light source, andadapted to supply,

at the tap and the second end of the secondary,

alternating current for heating a light source preliminary to operation, the tap and the second end of the secondary being connected to a first light source, the output of the rectifier being connected to a second light source and means for substantially simultaneously disconnecting the output of the rectifier from the second light source and connecting the secondary of the transformer at the tap and the first end thereof to the second light source.

13. The method of operating a 'pair of light sources which comprises supplying direct current to one light source while heating the other light source preliminary to its operation with alternating current of less than the operating value required by said lamp. v

14. The method of operating a pair of light sources which comprises supplying direct current to one light source while heating the other light source preliminary to its operation with alternating current of less than the operating value required by said lamp and upon the shut-- ting off of the direct current to the first light source supplying alternating current of the proper operating value to the first light source.

15. In combination, an alternating current supply line, a plurality of light sources, a transformer having its primary connected to the current supply line and having a tapped secondary, the secondary being adapted to supply alternating current for operating a light source at the tap and one end of the secondary, and adapted to supply alternating current for heating a light source preliminary to its operation at the tap andthe second end of the secondary, the secondary being connected at the tap and the first end thereof to one light source and connected at the tap and the second end thereof to a second light source and means for interchanging the current supply to each of said light sources.

16. In combination, an alternating current supply line, a plurality of light sources, a transformer having its primary connected to the current supply line and having a tapped secondary, the secondary being adapted to supply at two of its terminals alternating current for operating a light source, said terminals being connected to one light source, said secondary also being adapt ed to supply at two of its terminals alternating current for heating a light source preliminary to its operation, said last-mentioned terminals being connected to a second light source and means for interchanging the current supply connected to said light sources. I

1'7. In combination, an alternating current supply line, a plurality of light sources and a transformer having its primary connected to the current supply line and having a tapped secondformer having its primary connected to the current supply line and having a tapped secondary, the secondary being adapted to supply at two of its terminals alternating current of a value sufiicient to illuminate said light sources to full brilliance, said secondary also being adapted to supply at two of its terminals alternating current of a lesser value for heating a light source preliminary to its normal operation, said lastmentioned terminals being connected to a light source'and switching means for connecting said light source to the first-mentioned pair of'terminals.

19. In combination, an alternating current supply line, a plurality of light sources, a transformer having its primary connected to the current supply line and having a tapped secondary.

the secondary being adapted to supply at two of its terminals alternating current for operating a light source, said terminals being-connected to onelight source, said secondary also being adapted to supply at two of its terminals alternating current for heating a light source preliminary to its operation, said last-mentioned terminals being connected to a second light source and means for substantially simultaneously disconnecting one of said pairs of terminals from the light source to which it has been connected and light source.

connecting it to a third GEORGE FRIEDL, 

